1. Field of the Invention
The present invention is generally in the field of semiconductors. More specifically, the invention is in the field of semiconductor substrates for fabrication of optical components and bulk silicon electronics.
2. Background Art
Different substrate requirements for optical components, such as waveguides, gratings, and modulators, and bulk silicon electronic devices, such as bulk silicon electronic devices formed using Bipolar Complementary-Metal-Oxide-Semiconductor (“BiCMOS”) technology, hinder the integration of optical components and bulk silicon electronics on a single substrate. For example, optical components can be optimized on a Silicon-On-Insulator (“SOI”) substrate having a thin silicon layer situated over a thicker buried oxide layer, which is in turn situated over bulk silicon. In a SOI substrate that is optimized for optical components, the thin silicon layer in the SOI substrate can have a thickness of, for example, a few thousand Angstroms. However, bulk silicon electronic devices, such as silicon-germanium (“SiGe”) bipolar transistors and other devices formed using SiGe BiCMOS technology, require much thicker silicon, such as silicon having a thickness of hundreds of microns.
Optical components have been fabricated using Silicon-On-Saphire (“SOS”) technology, which takes advantage of a transparent saphire substrate. However, an undesirably high defectivity rate in SOS substrates reduces the feasibility of integrating optical components and bulk silicon electronics on a SOS substrate. Additionally, the cost of the SOS substrate is very high.
Thus, there is a need in the art for a semiconductor substrate for effectively integrating optical components and bulk silicon electronic devices, such as devices formed using SiGe BiCMOS technology.